Centrifugal fan or pump.



PATENTBD 00T. 1o, 1965,

s. C. DAVIDSON. GBNTRIPUGAL PAN 0R PUMP.

' APPLICATION FILED APB. 25,1904.

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PATENTED 00T. l0, 1905.

G. 'DAVIDSON GBNTRIFUGAL PAN 0R- PUMP APPLIOYATION FILED APB `25,1904

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showing 'a fan with a d enteran sfr-arras .arnivfr eww@ satmnnctnnann navmson, oir-BELFAST,

'CEN-rarement.

To (tlf .v1/:hom mrtf/ concern:

Bc it known that I, SAMUEL CLELAND DA- soN, merchant, a subject ot' the King of jritain and Yireland` residin in Belfast, have invented certain new and useful .i iements in or Relating to Centrifugal Fans or Pumps, of which the following is a specification.

My improvements refer to the Vtypeof centrifugal fansor pumps (hereinafter referred to as fans) described in the specification of previous Letters Patent granted to me and dated November 27, 1900,l No. (562,395, hereinafter referred to as my previous specic'ation. Y

Now the object of my present invention is to improve the working etliciency of fans of this or similar types, especially for certain duties. fx

According to this invention the blades of the fan-Wheel have within their circular path an unobstructed chamber, and covenplate is litted upon or closely "adjacent to the intake ends of the blades, so as to leave an inletopening or eye-of smaller diameter than that of the circle described by the inner edges of blades. whereby there is formed a cylin' drical Zone or space, (hereinafter referred to as the v"cylindrical zone 'space,) which is bounded exteriorly by the inner margins of the blades and' laterally upon the side toward the eye by said cover-plate and which `cylindrical Zone space is free of obstruction tfromthe inner margins of the blades t e the circumference of tbe inlet or eye of said plate, so that the fluid can onllreuter 'the center of the fan\.vhf-el axially through said eye and thence through said cylindrical more particularly radiate ou tira rd ly Ione space to the blades.

` to the accompanying drawings ll fully explain the nature of my inven4 d how the une carried into effect.

gure 'l is a ver tical sec n-whcel made in accordance `with invention. Figs. 2, 3, and et are similar views to Fig. l, showing three moditied'const-ructions. 5 is a section of the improved Vfan-wheel in the plane of revolution on' line uf l/ of Fig. El looking in the direction of the arrow y. Fig. 6 is a similar view to Fig. 5,

iffeyrent form of blade.

Referring now to Fig. l, A is the fan-shaft; l, the hub of thefan-wheei, mounted on shaft n.. (l is a circular disk-like extension of the huh B. E represents vanos or blades riveted 'i lends E' toa disk D, which is fastened Specification of Letters Patent. 'Application flied April 25, im.vv serai No.- 204,922. Y

instaan" France Punks-2., i

Patented oct. 10,1905.

tothe disk-like extension C.' ffis'a cover: platein the form of an otherwisefastened to theiintalre ven dsof the blades E. G is the i the annulus l? and corresponds vvitlithat of the dish D. 'H `indicates the inner edge of the. annulus F and the circu i or intake-opening 0 of the circle described by the inneredges'ofrthe fan-blades E and the outer circumference of a 4cylindrical zone space indicating the interiorv cylindrical zone space depth of said cy 4ed by thecircle shallow as com central intal'ce-op'ening O in the annulusF. This. construction is adapt-ed forja large volumetric output (relatively to the c liameteif'. of the fan)` against low resistances either of, hack pressure or suction. i

circumference of -,the Z. V- In Fig. l'the radial lindrical zone spaceibound- J and K, is shown relatively in 2, where similar letters offrefer ence are used.y thediameter ot' vth or intake-opening O in the annulus'F isshown relatively less than in Fig. L wherebyfthc radial depth of the cylind greater than in Fig. ll. adapted for smaller high resistances of e. central eye rllhis construction is volumetric output against back pressure or suction. Fig. 3. Where similar letters of reference are employed, with theexception d f those relating to the annulus,'a construction is shown which is adapted for similarfduties 'to `those provided for in Fig-1,v it being, however. modied, in that a fixed or.non-rotating annulus F is employed to laterali the intake en d ofthe fan-Wheel `Zone space Z. This fixed annulu'si-s mounted upon the 'fa'nJcasing as close as possibletci the intake ends of the blades il" which in this for/m .are shown as connected by an annular Dif-te E?) which annular plate corresponds in diameter with the circle described by the vinner edges of the blades. The clearancef-space M be o u tercircumference of Z.- yK is a dotted lineiical zone space is annulus riveted. or

inference of 4the[eye y the fan. `Jir'idlcates pared with the diameter of the v y incluse "at the cylindrical f, riveted to the blades E, the inner edgeibf IOC) tween the rotating annulus F and' the liXed,

annulus F' ispreferabl fan is running at high speeds. This construction, however, involves a slight lossiof mechanical strength and rigidityat theintake ends of the blades for veryhigh .speedsotL revolution as compared with the construction shown in Figs. 1 and 2. Y v

In Li a further modified construction is shown, wherein l) is a cast-metal circular y made as small as pos .sible consistent with freerotatlont whenfthe IIO plate inclosing on the outer side of the fanwheel hub B and disk D the opening in the fan-casing around the fan-shaft A. 1) represents radial fins extending from the circumference of the metal plate P inward to stiffen the central part thereof around the shaft. Q is a gas or water tight gland mounted at the center of the circular plateP and fitted around the shaft A to prevent leakage of iuid into or out of the fan-casing on the sideo'pposite the inlet O. This figure shows the annulus F, which for high speeds -of rotation is of similar construction to that shown in Fig. i, in Combination with a fixed annulus F, which is shaped to correspond with the' outer circumference of the cast-metal plate P on the opposite side of the casing, whereby both ends of the fan-wheel blades are the same distance from the sides of the fan-casing, Apartfrom the special construction of plate P and adjacent parts thereference-letters are thc same as in Fig. 3. This construction of fan is adapted for dealing with gas or acting' as a centrifugal pump.

in the construction of the fan-blades shown in the drawings both ends of the same are made exactly alike, with flanges formed thereon at right angles to the axis of the blades in the same manner as described in my previous specification for those ends which are riveted to the fan-Wheel disk, and to the opposite ends of the blades which project from the fanwheel disk l apply and rivet thereon the annulus F, which is cut, preferably, out of afiat metal sheet,the outercircum ferenceGof which annulus F is of equal or rather larger diameter than that of the circumference of the circle described by the outer edges of the fan-blad es and the inner circumference of either equal or less diameterthan that of the circle described by the inner edges of the fan-blades, according to whether the said annulus forms the means for' inclosing the cylindrical zone space or Whether an .adjacent covenplate is employed for this purpose. When the inner circumference of the annulus F is of less diN ameter than the circle in which .the inner edges of the blades revolve, the said inner edge is preferably curved or dished inward toward the fan-wheel disk, as shown at H in.

Figs. 1', 2, and fl of thedrawings, whereby the stiffness and strength of said annulus is greatly enhanced, and a rounded-over edge is present- Aedito the fluid entering the center of the iiange;

which minimizes the een@ conzmcta effects in regard to the iniow of said fluid, and forsame reasons the fixed annulus F' is preferably made with its inner edge rounded over, as shown in Figs and 4. I preferably make the rivet-holes in said annulus F which connects the intake end of the blades to exactly corn respond with those in the fan-wheel disk D to which the other ends of the blades riv eted, and when said blades are accurately Hanged to length and "the rivet-holes accurately located therein the riveting of said annulus upon the intake ends of the blades ining in a perfectly true running circle relatively to the plane of revolution of the fanwheel disk and to theaxis of the fan, and the rigidity of the whole fan-wheel when thus constructed is such that it will stand being driven at the highest speeds employed in practice without deviation from true rotation.

Figs. 5 and 6 show the boundaries of the cylindrical zene spacein front elevation andalso show the preferred proportion of blades EE. wherein the passage-way n between said blades is substantially greaterin radial measurement lthan the widest space between the blades measuredv circumfcrcntially. The crosssectional shape of the blades of the fan may be of any suitable type. For instance, they may be curved, as shown in Fig. 5, or radial, as shown in Fig. 6,

rlhe axially-directed arrows shown in Fig. 2 indicate the direction of flow of the fluid through the inlet-olicning O, and the radiallydirected. arrows indicate the direction of flow through the cylindrical zone space Z, which flow is radial when the fan is operating with free intake and free discharge; but when operating against resistances eitherron the suction or discharge this flow is both radial and circumferential when said fans are employed without an inclosing casing, the outward radial iow being through about the half-length of lthe blades nearest the disk D and mainly circumferential within the circle of the inner tedges of the other half, which is nearest the annulus F. It is essential that the space within the blades should be so free from obstruction that thesc currents should'not be broken up or seriously disturbed, as by such action the efiiciency of the fan is materially reduced. 'When operating inside a spirallyshaped casing or housing, the circumferential iiow is very marked within the whole ference of the spiral is closest to the fan blades and extends, according to the strength of the resistance relatively to the periphery speed of the blades, for more or less half-way round the circumference of the interior circle of the blades, and for part of this circumference when the resistance is strong relatively to the periphery speed of the blades its velocity of flow is considerably higher thun the speed of rotation of the inner edgesof the blades. Hence if any of thc inne-'- edges of the blades projected inside the circle described by the inner edges of the blades at J toward the inner circumference of the cylindrical zone space their effect would be to check this high velocity of circumferential flow of the fluid in the cylindrical zone space, i and thereby materially reduce the pressure sures the intake end of the fan-wheel revolv length of the blades from where the circum- IOO LII

-described may have blades mounted on one or or suction set up by the fan for a given speed of rotation and decrease the mechanical eliiciency ofy the fan relatively to the duties pen formed. Itis therefore .of importance that the said cylindrical zone space be free from any obstructions whatever to either theradial or circumferential viiow of fluid through or Within it.

It is obvious that fans constructed as above both sides of the fan-wheel-disk C D.

Whatl. claim, and desire to secure by Letters Patent, is-

l. A centrifugal fan oi* pump in which the iiuid enters axially and discharges radiallythe rotary member orf fan-wheel comprising a se.

ries ot' elongated blades of substantially the same depth throughout having within their circular path an unobstructed chamber, and a cover-plate at the inlet side, closely adjacent to the intake ends of the blades, and having an eye smaller than the circle described by the inner edges oi' the blades and forming a Zone' space, said space bounded exteriorly by the circular path in which the blades revolve and laterally by the said plate, and extending in- Wardly free of obstruction to the circumference of the inlet-opening or eye of said plate, sc that the fluid entering thefan-Wheel axially through said eye circulates thence outwardly Y through said zone space to the blades.

2. A' centrifugal fau or pump in which the duid enters axially anddischarges radially, the rotary member or fan-wheel comprising a se-4 ries of elongated blades oi' substantially the same depth throughout having within their circular path an unobstructed chamber, and a cover-plate fastened to the. inlet ends of the blades, and having a concentric eye smallerv than the circle described by the inner edges of the blades, closely adjacent to the intake ends of the blades, whereby a cylindrical zone space is formed which is bounded exteriorly by the circular path in which the blades revolve and laterally by said cover-plate, andextendinginwardly, free of obstruction to the circumference of the inlet-opening or eye of said plate, so that the fluid entering thean-wheel axially through said eye circulates thence outwardly through said Zone space to the blades.

3. A centrifugal fan or pump in which the luid enters axially and discharges radially, the rotary member or fan-wheel comprising a series of blades having within their circular path an unobstructed chamber, and a cover-plate at the inlet side, closely adjacent to the intake ends of the blades, and having an eye smaller than the circle described by the inne'r edge of the blades, and said eye entering partly within the intake ends of the blades, said plate vforming a zone space bounded exteriorly by the circular path in which the blades revolve, and laterally bythe said/plate, and extending invby the said plate,

Wardly freeo obstruction to the circumference of the inlet-epening or eye oi' said plate, so that the fluid entering the fan-wheel axially through said eye circulates thence outwardly through said Zone space .to the blades.

l. in a centrifugal fan orpump, a rotary member or fan-wheel comprising a series of blades havingwithin their circular path an unobstructed chamber, and an annular plate to which the inlet ends of the blades are fastened, said plate having a concentric eye of smaller diameter than that of the circle described by the inner edges of the blades.

5. A centrifugal fan or pump in which the .fluid enters axially and discharges radially, the rotary. a series of blades having within their circular path an unobstructed chamber, and a coverplate at the inlet side, closely adjacent to the intake ends of the blades, and havingan eye smaller than the circle described by the inner edges of the blades and forming a zone space, said space bounded exteriorly by the circular path in which the blades revolve and laterally and extending inwardlyf free of obstruction to the circumference of the inlet-opening or eye of said plate, so that the fluid entering the fan wheel axially through said eye circulates thence outwardly through said Zone space to the blades, .said rotary member or fan-wheel being uninclesed whereby the duid discharged from its blades may freely escape tangentially therefrom in all directions;

6. A centrifugal fanor pump in which the iiuid enters axially and discharges radially, the rotary member or fan-'Wheel comprising numerous elongated blades arranged length- Wise in approximately axial direction, and in member or fan-wheel comprising substantially drum form, so as to inclose within them a relatively large and practicall, unobstructed intake-chamber, and a coverplate at the inlet side, closely adjacent to the intake ends of the blades, and having an eye smaller than the circle described by the inner edges of the blades and forminga zone space, said space bounded exteriorly by the circular path in which the blades revolve, and laterally by the saidplate, and extending inwardly free of obstruction to the circumference of the inlet-opening or eye of said plate, so that the duid entering the fan wheel axially through said eye circulates thence outwardly through said zone space to the blades.

7. A centrifugal fan or pump in which the Huid enters axially and discharges radially, the rotary member or fan-wheel ITO numerous elongated blades arranged length-1 "wise mapproximately axial direction,` and in .substantially drum i'orm, so as Ato inclose within them a relativelylarge and practicallyn unobstructed intake-chamber, and spaced apart a distance no greater than twice their radial depth, and a cover-plate at the inlet side, closely adjacent;i to the intake ends of the blades, and having an eye smaller than 5 eye circulates thence euhvardly through smid 10 the Circle described by the inner edges of the l Zone space te the blades. blades and forming' u zone space Said space l ,ln \\'itness whereof I have hereunto slgned beunded exteriorly by the circuler path in my name in the presence of two .subscribing which die blades revolve, and laterally by the witnesses. said platei and extendimer inwardly free of SAMU )L CLEMND DAYIDNLY Obstruction to the circumference of the inle- Witnesses:

'opening or eye of said plate, so that the iuid EDWARD FERGUSON, entering the fan-wheel axially through said 'JOHN JOHNSDN. 

